An example of known hermetic compressors of this type is one in which an electric motor is integrally provided on top of a compression mechanism and a coil spring is interposed between the compression mechanism and the inner surface of the bottom wall of a sealed housing to inhibit the transmission of vibrations of the compression mechanism and the electric motor to the sealed housing and thereby reduce the noise of the compressor in operation (see, for example, Patent Document 1: Japanese Unexamined Patent Publication No. H01-203688 (Pages 3 and 4 and FIG. 1)).
In the above hermetic compressor in Patent Document 1, the upstream end of a suction passage is open at the sealed housing below the compression mechanism and a suction pipe is connected to the opening of the suction passage to extend to the outside of the sealed housing. Gas led through the suction pipe into the sealed housing is sucked into a compression chamber of the compression mechanism, compressed therein and then discharged through a discharge port into the sealed housing. Thereafter, the discharge gas in the sealed housing is led to the outside through a discharge pipe connected to the sealed housing.
Problems to be Solved
As described above, the hermetic compressor in Patent Document 1 employs a structure that gas compressed in the compression mechanism is discharged into the sealed housing. In this hermetic compressor, the sealed housing is filled with high-pressure discharge gas, so that the pressure of the discharge gas acts on the compression mechanism and the electric motor placed inside the sealed housing. On the other hand, low-pressure suction gas is led through the suction passage into the compression mechanism. In other words, the pressure of the suction gas acts on part of the compression mechanism in which the suction passage is formed. Therefore, a downward force acts on the compression mechanism owing to the difference between the discharge gas pressure and the suction gas pressure, so that the compression mechanism and the electric motor are pushed down.
If, like this, a downward force acts on the compression mechanism and the electric motor, the coil spring supporting both these components must bear both the gravity acting on the compression mechanism and the electric motor and the force due to the gas pressure difference. Therefore, the coil spring should be hardened accordingly, which causes a problem that vibrations transmitted from the compression mechanism and the electric motor to the sealed housing are increased.
Further, in order to prevent vibrations produced in the compression mechanism and the electric motor from being transmitted to the sealed housing, it is necessary to always keep the compression mechanism and the electric motor away from contact with the sealed housing. Therefore, if the positions of the compression mechanism and the electric motor are shifted inside the sealed housing because of the difference between the discharge gas pressure and the suction gas pressure as described before, this invites the need to ensure a larger clearance than necessary between the housing and the compression mechanism. As a result, a problem arises that the sealed housing is upsized.
The present invention has been made in view of the above points and its object is to restrain that when the compression mechanism and the electric motor are resiliently supported in the sealed housing, the positions of the compression mechanism and the electric motor are shifted because of the difference between the discharge gas pressure and the suction gas pressure, thereby achieving size reduction and noise reduction of the hermetic compressor.